Aerial tankers use refueling booms to fuel other aircraft in mid-flight. In this fashion, the refueled (receiver) aircraft can fly extended missions during military or civilian operations. Generally, the aerial tanker and the receiver aircraft must be flown in close proximity to accomplish a refueling. Given this proximity, a manual operator in the aerial tanker may extend its refueling boom to mate with the fuel tank of the receiver aircraft.
In general, the refueling boom operation is dangerous and can tax the skill of even experienced boom operators. In addition, the refueling boom may improperly mate with and thus damage the receiver aircraft. For example, a stealth aircraft may have its low observable coating damaged such that it becomes observable to enemy radar. In such a case, the stealth aircraft may have to abort its mission and return for repair.
During the refueling operation, the boom operator must manually direct the refueling boom to mate with the receiver aircraft. This manual direction must be accomplished in varied lighting conditions from extremely bright sun light to complete darkness or minimum visibility weather conditions. Moreover, the manual direction may be further complicated by turbulence. Because of this manual operation, refueling operations are lengthy as compared to machine-guided refueling. In addition, the need for human boom operators makes unmanned aerial tankers unfeasible. Finally, manual operation is inevitably prone to error and mishap.
Conventional machine-guided boom controls typically use an electro-optic sensor to estimate the boom and receiver aircraft position. By removing the need for human boom operators, unmanned aerial tankers can be developed, which can lead to significant cost savings. For example, it has been estimated that manned aircraft use 80% of their service life to train aircrews. Conventional electro-optic boom automated boom control thus advantageously lessens the need for human operators. However, although electro-optic sensors can be quite accurate, they are range limited. Moreover, sensors can fail, thereby jeopardizing the resulting automated control of the refueling boom.
Accordingly, there is a need in the art for more robust machine-guided boom control systems that detect sensor failure and reconfigure in light of any detected sensor failure.